With its slim design, the UL Listed Resistor Power Bank with Power Check gives you the added power you need without the added weight. With a 4,000 mAh/14.8Wh Grade A Lithium Polymer battery and a 5V/1A output, you can charge your smartphone at the same rate as most wall outlets. The power check display tells you exactly how much power is left in the battery backup. Includes a USB-to-Micro-USB connecting cable which can recharge the battery backup or other devices with a Micro USB input, like Android Smartphones from Samsung®, Motorola®, HTC®, Nokia®, and others. This product has passed UL standard. Power banks are permitted in carry-on luggage only, and at the discretion of TSA agents.